Positioning stages are motor-driven machines, typically with linear travels, that can be employed to, e.g., to move goods/products. Positioning stages are employed in industry to move a carriage or slide in a direction along a path in connection with a variety of applications. For example, a good can be placed upon the slide at an initial position, after which the slide can be moved to a next position (or positions) where some work or activity is performed on the good, and, finally, the slide can be moved to a final position of the stage where the good can be removed from the slide. The slide can then return to the initial position and the process can be repeated. In this example, the good can enter as an unfinished good and leave the stage as a finished good. At the next position(s), the work performed can be completed by a machine that requires a relatively precise location of the good.
Accordingly, positioning stages can be used in a variety of different environments depending on the application. Although the variety of different environments can differ in many ways, one thing that is virtually universal is that the positioning stage will be exposed to many forms of contaminants. For example, the positioning stages can be employed in connection with a box folding plant that produces substantial by-product dust and debris from the boxes; a factory handling glass or glass panels wherein breakage is often inevitable creating shards and highly abrasive particles; to laser trimming/etching, wafer drilling, etc. wherein contaminants are certain to be created as a result of the work activity.
Also depending upon the application, the positioning stage may be required to operate within certain ranges of speed, precision, and lengths of travel. However, the numerous types of contaminants present can infiltrate the stage and cause potential wear and damage as well as interfering with the speed and precision expected. Therefore, protection of the internal components of a positioning stage can become a critical requirement in applications with any kind of contamination, and can present substantial design challenges for the stage designer. Positioning stages can have, e.g., mechanical, optical, magnetic and electrical components in their interior, none of which may operate well or very long in contaminated environments. In addition, many of these contaminants can be very abrasive, compounding the wear and erosion of the stage and/or its internal components.
In an effort to protect stages, many conventional systems employ a cover or cover plate that that shields the internal components from falling debris. However, since the slide that moves the product must be accessible above the cover while the mechanisms that move the slide must be below the cover to be protected, conventional systems inevitably lead to holes in the protection afforded by a cover plate. Today, a number of protection schemes are commonly used on positioning stages, such as collapsible bellows, metal strip seals, and re-circulating belts. While each of these schemes can provide some advantages, there are drawbacks for each scheme as well.
Protective bellows are relatively simple to implement and are perhaps the most widespread, but bellows are a very expensive protection scheme and are less effective with airborne contamination and/or small contaminants. Metal strip seals offer better protection from particles of all sizes, but conventional designs have the seals on the top of the stage, which suffers from debris accumulation on the seals, and typically requires a higher level of maintenance. Re-circulating belts are unsuitable for some environments, (especially wet environments where bellows and strip seals are vastly superior) and get succeeding less effective as the particle size decrease.
Moreover, certain materials have been demonstrated to be capable of collecting or capturing contaminants before they can enter the inside of a stage, yet conventional positioning stages do not make use of these materials. Further, in addition to the difficulties presented by contaminants, the existing protection schemes also suffer from other deficiencies in their design. For example, conventional positioning stages are particularly susceptible to vibration, especially at higher speeds, and sagging of the central members of the stage, such as the cover plate and/or the strip seals. Both of these difficulties can arise due to a lack of support and/or a lack of an effective means of coupling to more stable components.
In view of at least the above, there exists a strong need in the art for a system and/or methodology that can facilitate a reduction of contaminants that can harm the internal components of a positioning stage, support the central members, and/or reduce the vibrations.